Rear end #3 DEAD!

Cummins Driver

Cummins Driver

THE Cummins Driver
Joined
May 16, 2007
Messages
2,405
Gosh, am I ever getting tired of this:bang

Owned this truck for 80k miles. Original Dana 70 let go about 185k(about 22k after i bought the truck). So i bought a used Dana 70 and paid too much for it and it lasted another 35-40k before it died from the same death the first one did(busted pinion gear with stress cracks all throughout). So in the mean time i had bought a supposedly good Dana 80(that i payed too much for again). I drug it out, opened it up, and it was shot on the inside:bang I noticed the pinion shaft was loose, so I took the nut off and pulled the yoke. Needless to say, bearings fell out when i did. :doh: I also noticed that one of the pinion bearings had spun in the housing causing it to wear down some and not be a good press fit for a new bearing. Well, I talked to a knowledgeable friend on rear ends and he said it could be fixed and shouldnt be a problem. So i bought $650 worth of new yukon gears and bearings for the Dana 80 and had a local boy put them in and set it up. He used some stuff for the pinion bearing that went around it and was supposed to harden up like metal to fill the small gap that was there and keep it from spinning again.

So i noticed yesterday that i had a very noticable vibration between 30 and 40mph and not really anywhere else. I thought it was the rear u-joint, but when i took it out, I noticed I could grab the pinion shaft and slightly move it up and down by hand:badidea: Only been running it for 10-15k miles. Pulled it twice and daily driving with some towing other than that.

So anyways, I havent pulled it apart yet. It wasnt making any noise, and the U-Joint was a little loose so im hoping that was where the vibration was coming from, but if my gears are shot, I will be finding another whole rear end of some kind. I dont much care what it is as long as it is cheap at this point. Would like to have another D80 for it though if this one cant be fixed. I guess best case scenario at this point is that the gears are still in good shape, and I can somehow get the bearing back into the housing tight, as im sure that is where the play is coming from.

It sure is getting aggrovating that i cant keep a rear end in an automatic(no banging gears) daily driven 350hp street truck.

Anyways, I mainly needed to vent at this point, but any suggestions or ideas you guys have are welcomed. I guess I will probably start working on it when i get home from school today.

Driving moms mini van today:bang

Eric
 
Don't fell bad! We Shattered 3 Dana 70 in 5weeks but we are getting good @ taking them apart & rebuilding them!! But do see your point, it is starting to be like old news breaking like that all the time!!
 
Yeah, i does get old.

I dont think pulling is what killed this one though. I think it would have done the same thing had i not pulled it at all, I just think it might have taken longer for it to get loose.

Eric
 
Cummins Driver said:
Gosh, am I ever getting tired of this:bang

Owned this truck for 80k miles. Original Dana 70 let go about 185k(about 22k after i bought the truck). So i bought a used Dana 70 and paid too much for it and it lasted another 35-40k before it died from the same death the first one did(busted pinion gear with stress cracks all throughout). So in the mean time i had bought a supposedly good Dana 80(that i payed too much for again). I drug it out, opened it up, and it was shot on the inside:bang I noticed the pinion shaft was loose, so I took the nut off and pulled the yoke. Needless to say, bearings fell out when i did. :doh: I also noticed that one of the pinion bearings had spun in the housing causing it to wear down some and not be a good press fit for a new bearing. Well, I talked to a knowledgeable friend on rear ends and he said it could be fixed and shouldnt be a problem. So i bought $650 worth of new yukon gears and bearings for the Dana 80 and had a local boy put them in and set it up. He used some stuff for the pinion bearing that went around it and was supposed to harden up like metal to fill the small gap that was there and keep it from spinning again.

So i noticed yesterday that i had a very noticable vibration between 30 and 40mph and not really anywhere else. I thought it was the rear u-joint, but when i took it out, I noticed I could grab the pinion shaft and slightly move it up and down by hand:badidea: Only been running it for 10-15k miles. Pulled it twice and daily driving with some towing other than that.

So anyways, I havent pulled it apart yet. It wasnt making any noise, and the U-Joint was a little loose so im hoping that was where the vibration was coming from, but if my gears are shot, I will be finding another whole rear end of some kind. I dont much care what it is as long as it is cheap at this point. Would like to have another D80 for it though if this one cant be fixed. I guess best case scenario at this point is that the gears are still in good shape, and I can somehow get the bearing back into the housing tight, as im sure that is where the play is coming from.

It sure is getting aggrovating that i cant keep a rear end in an automatic(no banging gears) daily driven 350hp street truck.

Anyways, I mainly needed to vent at this point, but any suggestions or ideas you guys have are welcomed. I guess I will probably start working on it when i get home from school today.

Driving moms mini van today:bang

Eric
Click to expand...


I can't see stuff that hardens like metal putting enough force on it, unless it has some expansion rate as it hardens. The race is a press fit.
 
Something was wrong with the D80, there is no way you should be able to kill it. I'd say get a differnt 80. Good luck man
 
You could have a machine shop press in a sleeve, but probably be cheaper to find another D80.
 
Well, i was worried about it, but it had a high rating pressure wise(cant remember what it was), and It was for this kind of application im pretty sure, but yes, Im 99% sure that is what happened is that it didnt hold up.

What do you guys think about tack welding the bearing race to the housing with the thing assembled? Is there any way it would work? Im not really worried about being able to reuse the axle housing if it would hold together for as long as the gears and bearings did. Im sure you wouldnt want to put too much heat to the bearings, but i dont see why some tack welds wouldnt hold it all tight without heating it up too much?

Like I said, I got screwed when i bought the D80 in the first place, and I was in a tight spot and thought this might work. Im pretty sure an 80 would be fine in my truck if the housing was all good and tight, so if there is no way for me to get this thing back together tight, ill be buying a whole nother axle in good shape.

Also, I wondered about buying an oversized bearing with the same inside diameter and pressing it in?

Thanks for the help and input.

Eric
 
Well, I took the pinion yoke off of it. I think the gears are good, but havent pulled the cover yet.

The front bearing race was spinning in the housing and loose, but not too bad. It hasnt spun much because it still looks just fine on the outside and inside of the race, and the bearing is fine. I have the bearing and race

Does anyone think it would be possible to weld a few spots around the outside of the race and grind them down smooth so that it would make up for the gap, and drive the race back in all the way good and flush? Or maybe put it in and carefully weld it around the edge of the race and housing?

Im hoping it is salvageable somehow.

Eric
 
Dang it Eric. I am thinking pulling hurt it also. Maybe cause you can spin as much as the higher HP guys the stress transferred to the rearend?
 
At 337hp/772tq i cant believe your having that many problems. I have almost 170K on my Dana 70 stocker and i have around 535 hp and 1200tq and have around 30-35 pulls on it and its still moving. Knock on wood. Sorry to hear about ur troubles...
 
It isn't that the stuff doesn't hold up, it is the fact that the race is a press fit. What you could do is take your current race turn down the OD, then use the goop, put in the smaller race and let it setup. I would probably have some shim stock in so you make sure you center your current. Let it setup, then put in your other race.
 
zstroken said:
It isn't that the stuff doesn't hold up, it is the fact that the race is a press fit. What you could do is take your current race turn down the OD, then use the goop, put in the smaller race and let it setup. I would probably have some shim stock in so you make sure you center your current. Let it setup, then put in your other race.
Click to expand...

Im not sure i follow what you are saying? I put the stuff around the race that is in it now and let it setup before the rear end was assembled. Why would it be different if the race was machined down and the same thing was done again? Just trying to understand a little better. Thanks

Eric
 
silverram323 said:
At 337hp/772tq i cant believe your having that many problems. I have almost 170K on my Dana 70 stocker and i have around 535 hp and 1200tq and have around 30-35 pulls on it and its still moving. Knock on wood. Sorry to hear about ur troubles...
Click to expand...

You have better luck than i do then! Both of my Dana 70's had a stress crack running along with each tooth around the outside of the pinion gear. Then they both broke a chunk out and also took some out of the ring gear. They both had close to 200k miles on them. I think this Dana 80 would have been fine had it never spun a pinion bearing so that i could have pressed the bearings in like they needed to be, but what can ya do when you are in a pinch?

Eric
 
Cummins Driver said:
You have better luck than i do then! Both of my Dana 70's had a stress crack running along with each tooth around the outside of the pinion gear. Then they both broke a chunk out and also took some out of the ring gear. They both had close to 200k miles on them. I think this Dana 80 would have been fine had it never spun a pinion bearing so that i could have pressed the bearings in like they needed to be, but what can ya do when you are in a pinch?

Eric
Click to expand...

You wouldn't happen to have any pics of these cracks as i would like to peel the cover off and take a look around in there. thanks
 
Hmm, Im not sure if I have any pictures of them or not. Im not sure that you could see them with the rear end all together though. I will see what i can round up for you. If I dont have a picture, I should be able to get one for ya.

Eric
 
Cummins Driver said:
Im not sure i follow what you are saying? I put the stuff around the race that is in it now and let it setup before the rear end was assembled. Why would it be different if the race was machined down and the same thing was done again? Just trying to understand a little better. Thanks

Eric
Click to expand...


To get the race to be a press fit. I would say a press fit is .001 smaller or so than the hole it goes into. The way your doing it is the same size.

If you had a decent machine shop, I would have them either weld it up and turn it back down or make a sleeve for it.
 
I picked up a core getrag, that had spun the input bearing/race in the case. It has a tapered bearing on the input shaft, just the same as a pinion bearing. Anyways the machine shop put a sleeve in the case, and pinned it in there, then machined the sleeve out so the race is a press fit again.
 
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